Spatiotemporal evolution of the functional magnetic resonance imaging response to ultrashort stimuli.
Spatiotemporal evolution of the functional magnetic resonance imaging response to ultrashort stimuli.
复制标题
功能磁共振成像对超短刺激的响应的时空演化。
DOI：
10.1523/jneurosci.3986-10.2011
复制
发表时间：
2011-01-26
期刊：
影响因子：
--
通讯作者：
Silva AC
中科院分区：
文献类型：
--
作者：
Hirano Y;Stefanovic B;Silva AC
血流动力学响应函数（HRF）的特异性在空间上由血管结构决定，在时间上由血流动力学变化的演变决定。刺激持续时间对 HRF 的时空演变有额外的影响，因为短暂的刺激引发仅涉及局部脉管系统的反应，而长刺激则导致远程血管供应和引流的参与。在这里，我们使用功能磁共振成像来研究麻醉啮齿动物模型中血氧水平依赖性（BOLD）、脑血流量（CBF）和脑血容量（CBV）HRF与超短前肢刺激的时空演变。对单个 333μs 长刺激的 HRF 被可靠地检测到，并且包括 CBF 和 CBV 的快速响应，起始时间 (OT) 为 350ms，半峰全宽为 1s。相比之下，较长的刺激会引起含氧血液在皮质微血管中的分散传输，从而显着延长 CBV HRF 的进化，但不会延长 CBF 的进化。 CBF 和 CBV OT 表明血管活性信使在 350 毫秒内合成、释放并生效。然而，BOLD 和 CBV OT 之间的差异（约 100 毫秒）明显小于动静脉传输时间（约 500 毫秒），表明动脉对 BOLD HRF 的贡献。最后，随着刺激伸长，活动区域的快速生长表明功能性充血是一个涉及整个功能性皮层深度的综合过程。这些发现为大脑功能性血流动力学调节的时空动力学提供了新的视角。
The specificity of the hemodynamic response function (HRF) is determined spatially by the vascular architecture and temporally by the evolution of hemodynamic changes. The stimulus duration has additional influence on the spatiotemporal evolution of the HRF, as brief stimuli elicit responses that engage only the local vasculature, while long stimuli lead to the involvement of remote vascular supply and drainage. Here we used fMRI to investigate the spatiotemporal evolution of the blood oxygenation level-dependent (BOLD), cerebral blood flow (CBF) and cerebral blood volume (CBV) HRF to ultrashort forelimb stimulation in an anesthetized rodent model. The HRFs to a single 333µs-long stimulus were robustly detected, and consisted of a rapid response in both CBF and CBV, with an onset time (OT) of 350ms and a full-width-at-half-maximum of 1s. In contrast, longer stimuli elicited a dispersive transit of oxygenated blood across the cortical microvasculature that significantly prolonged the evolution of the CBV HRF, but not the CBF. The CBF and CBV OTs suggest that vasoactive messengers are synthesized, released and effective within 350ms. However, the difference between the BOLD and CBV OT (~100ms) was significantly smaller than the arteriolar-venular transit time (~500ms), indicating an arterial contribution to the BOLD HRF. Finally, the rapid rate of growth of the active region with stimulus elongation suggests that functional hyperemia is an integrative process that involves the entire functional cortical depth. These findings offer a new view into the spatiotemporal dynamics of functional hemodynamic regulation in the brain.